Detect and handle symlinking of plugins in plugin_basename().

props rmccue, MikeSchinkel, jdgrimes.
see #16953.


git-svn-id: https://develop.svn.wordpress.org/trunk@27158 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/plugins.php

@@ -143,6 +143,7 @@ if ( $action ) {
 			@ini_set('display_errors', true); //Ensure that Fatal errors are displayed.
 			// Go back to "sandbox" scope so we get the same errors as before
 			function plugin_sandbox_scrape( $plugin ) {
+				wp_register_plugin_realpath( WP_PLUGIN_DIR . '/' . $plugin );
 				include( WP_PLUGIN_DIR . '/' . $plugin );
 			}
 			plugin_sandbox_scrape( $plugin );